A common issue regarding the rental/lease of automobiles, trucks, motor vehicles, and other fuel consuming systems is the management and accounting for fuel use within these fuel consuming systems and proper chargeback to the rental/lease customer for situations in which fuel is consumed but not replaced by the customer. Typical approaches to this fuel accounting methodology require that the rental/lease agency issue the motor vehicle with a “full” fuel tank and require that the customer return the motor vehicle with a “full” fuel tank. If the customer returns the vehicle with a fuel gauge indicating anything less than a “full” tank, the rental/lease agency generally refills the fuel tank to a “full” level and charges the rental/lease customer appropriate fees based on the vehicle rental/lease contract.
While minor discrepancies in fuel tank contents may seem insignificant in the overall profitability in the rental/lease vehicle market, it should be noted that the rental car market in the United States has annual revenue of approximately USD$21 billion, with a fleet of approximately 1.6 million automobile rental vehicles (2010 data). This rental fleet services at least 22 million auto rental transactions per year (VISA® brand credit card rental car transaction count for 2004). This data would on its face suggest each transaction accounted for approximately USD$1000.00. However, a more realistic transaction value would be approximately one-quarter of this value, or approximately USD$250.00 (given that the transaction count cited was for a specific credit card vendor, and other credit card vendors are not included in this total). This analysis could easily yield 50+ million auto rental transactions per year. If each of these rentals is associated with a half gallon of unrecovered fuel cost, the total lost profit for this market could easily reach USD$100 million per year, or 0.5% of overall revenue, a significant profit loss given the overall profit margins in the industry.
Various fuel accounting issues are associated with this conventional prior art approach and include but are not limited to the following:                What constitutes a “full” fuel tank is extremely subjective, as the fuel gauges in most motor vehicles are generally nonlinear and subject to significant inaccuracies.        Customers may return the vehicle with less fuel than was originally in the fuel tank when the vehicle was issued to them, but due to inaccuracies in the fuel gauges of most vehicles this discrepancy may not be noticed, accounted for, or charged to the customer.        Refilling of fuel tanks by various rental/lease employees may result in inconsistent amounts of fuel in the fuel tank as the vehicle is issued to the rental/lease customer.        The definition of a “full” tank, as both defined by the vehicle rental/lease agency and the customer may have different meanings because neither party has an accurate method of determining fuel tank contents.        Since neither the rental/lease agency nor customer can determine the exact fuel tank contents, neither party has sufficient information as to how much fuel should be added to the fuel tank to constitute a “full” tank of fuel.        In many circumstances the vehicle rental/lease agency loses revenue on returned vehicles that contain less fuel than when the vehicles were issued, but the resolution of prior art fuel gauges do not permit the level of fuel tank level accuracy to properly account for these losses. As a result, vehicle rental/lease agencies may lose millions of dollars annually due to these unrecoverable fuel losses.        
The inability of vehicle rental/lease agencies to accurately manage their fuel costs can result in significant lost profits, as the fuel tank refilling charges account for a significant profits stream for these companies. However, to date no accurate methodology has been proposed to manage fuel recovery costs for these companies or to provide any methodology of defining a “full” fuel tank in these situations.